This is a common issue with older Soviet lenses, including the Jupiter 37AM. The grease used in these lenses often thickens or hardens with age, which can make the focus ring feel very stiff. Some visible grease near the mount is not unusual on this model and does not necessarily mean the lens is damaged.

Because the Jupiter 37AM uses a preset aperture design, even oily aperture blades are usually less of a practical problem than on auto-diaphragm lenses. On a digital camera with an adapter, it generally won’t affect camera operation.

You can try slowly working the focus ring back and forth through its full range several times; this may redistribute the old grease and improve the feel somewhat. If it remains very stiff, the proper fix is a clean-and-regrease of the focusing helicoid with suitable helicoid grease.

So: it’s probably not “corrupted,” but stiffness from aged lubricant is a known maintenance issue. Keep it if the optics are good, unless you specifically want to avoid servicing an old manual lens.